The Kalapana, Hawaii, M_W 7.7 earthquake on November 29, 1975 generated a local tsunami with at least 14.3 m runup on the southeast shore of Hawaii Island adjacent to Kilauea Volcano. This was the largest locally generated tsunami since the great 1868 Ka'u earthquake located along-shore to the southwest. Well-recorded tide gauge and runup observations provide a key benchmark for studies of statewide tsunami hazards from actively deforming southeast Hawaii Island. However, the source process of the earthquake remains controversial, with coastal landsliding and/or offshore normal or thrust faulting mechanisms having been proposed to reconcile features of seismic, geodetic, and tsunami observations. We utilize these diverse observations for the 1975 Kalapana earthquake to deduce a compound faulting model that accounts for the overall tsunamigenesis, involving both landslide block faulting along the shore and slip on the island basal décollement. Thrust slip of 4.5–8.0 m on the offshore décollement produces moderate near-field runup but controls the far-field tsunami. The slip distribution implies that residual strain energy was available for the May 4, 2018 M_W 7.2 thrust earthquake during the Kilauea-East Rift Zone eruption. Local faulting below land contributes to geodetic and seismic observations, but is non-tsunamigenic and not considered. Slip of 4–10 m on landslide-like faults, which extend from the Hilina Fault Zone scarp to offshore shallowly dipping faults reaching near the seafloor, triples the near-field tsunami runup. This compound model clarifies the roles of the faulting components in assessing tsunami hazards for the Hawaiian Islands.

中文翻译：

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1975 年卡拉帕纳、夏威夷、地震、山体滑坡和海啸的复合断层模型

Kalapana, 夏威夷, M _W1975 年 11 月 29 日发生的 7.7 级地震在夏威夷岛东南岸与基拉韦厄火山相邻的地方引发了至少 14.3 m 的海啸。这是自 1868 年发生在西南沿岸的卡乌大地震以来最大的本地海啸。记录良好的潮汐计和爬升观测为研究夏威夷岛东南部活跃变形的全州海啸灾害提供了关键基准。然而，地震的来源过程仍然存在争议，已经提出了沿海滑坡和/或近海法向或逆冲断层机制来协调地震、大地测量和海啸观测的特征。我们利用 1975 年卡拉帕纳地震的这些不同观察结果来推导出一个复合断层模型，该模型解释了整体海啸的发生，包括沿海岸发生断层的滑坡块和在岛基底部滑移。4.5-8.0 m 的海上décollement 推滑产生适度的近场爬升，但控制了远场海啸。滑移分布意味着残余应变能可用于 2018 年 5 月 4 日基拉韦厄-东裂谷带喷发期间的M _W 7.2 逆冲地震。陆地下方的局部断层有助于大地测量和地震观测，但不是海啸，因此不予考虑。在类似滑坡的断层上滑动 4-10 m，从 Hilina 断层带陡坎延伸到近海浅倾断层到达海底附近，使近场海啸上升三倍。该复合模型阐明了断层组件在评估夏威夷群岛海啸灾害中的作用。